Method and apparatus for processing seismic data

Abstract

Methods and apparatuses for processing seismic data carrying information about a subsurface structure are provided. One method includes splitting the seismic data in groups, each group including subsets of seismic data for which a distance from a respective shot point to a receiver line in a patch of active detectors corresponding to the shot point is within a predetermined range for the group, and extracting signal data for each block Hankel matrix based on an SVD analysis thereof. Another method includes extracting signal data by subtracting from seismic data an estimated noise model obtained by rank reduction of a Hankel matrix followed by dip filtering, enhanced based on a least square matching filter with the seismic data.

Description

BACKGROUND[0001]1. Technical Field[0002]Embodiments of the subject matter disclosed herein generally relate to methods and apparatuses for processing seismic data, more particularly, to adaptive rank reduction methods for attenuating (subtracting) the noise in recorded seismic data.[0003]2. Discussion of the Background[0004]During the past years, the interest in developing new oil and gas production fields on land and offshore has continued to increase. Therefore, geophysical surveys have become more sophisticated in order to more accurately decide where to drill to avoid a dry well. The term “geophysical survey” refers to a systematic collection of geophysical data using various techniques. The data may be collected from above, on or below the Earth's surface and the sea surface. Seismic methods (such as reflection seismology and seismic tomography) are the most frequently used techniques in geophysical surveys due to their efficiency in terms of penetration depth, relatively reduc...

AI Technical Summary

Benefits of technology

This patent describes a method for improving the separation of signals from strong coherent non-orthogonal noise in seismic data. The method uses a block Hankel matrix, a Singular Value Decomposition (SVD), dip filtering, and a least squares matching filter to adaptively model the noise and extract the signal data. The technique makes it possible to better separate the signal from the noise, which can be useful in imaging the subsurface.

Problems solved by technology

While this profile does not provide an accurate location for the oil and gas reservoirs, it suggests, to those trained in the field, the presence or absence of oil and / or gas reservoirs.

The seismic data may suffer from high levels of noise, making the task of processing and interpreting the data difficult.

Land seismic data is often overwhelmed by coherent noise, which, if not removed, renders the extracted information unreliable.

The spatial and temporal variations of phase velocity versus frequency and the high amplitude variations of noise lead to a poor signal to noise ratio.

When methods (such as, frequency and wave number—FK—fan filters) based on the assumption of regular detector spacing are used, smear artifacts occur in the subsurface image.

Other methods (such as frequency and distance from the source—FX—fan filters) that are adaptive locally are effective in removing the orthogonal coherent noise and are able to handle irregular geometry, but are unable to adequately attenuate aliased noise.

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